Abstract

BackgroundTumor suppressor gene p16 promoter hypermethylation has been widely studied in colorectal cancer (CRC), yet its clinicopathological significance remains controversial. The methylation alterations of other regions within p16 gene are still rarely researched. The present study aimed to explore the methylation changes of p16 gene body in CRC and to find whether they were associated with clinicopathological staging of CRC.MethodsPaired colorectal cancer tissues and corresponding adjacent normal tissues from 30 CRC patients were collected. The methylation levels of two CpG islands within p16 gene body, exon 1 and exon 2, were accurately assessed simultaneously by a LC-MS/MS method. The p16 protein expressions were assessed by immunohistochemistry assay. Statistical analyses were carried out using SPSS 17.0 software. Heat-map analysis was carried out by HemI 1.0 software.ResultsIn the present study, CRC tissues showed more highly methylated than adjacent normal tissues at both CpG islands of p16 gene. And exon 2 hypermethylation was higher and more frequent than exon 1. The ROC curve analysis showed that the simultaneous use of both indicators had excellent sensitivity and specificity for distinguishing CRC tissues and adjacent normal tissues. Following, the methylation level of p16 exon 1/2 was negatively related to p16 protein expression. Further correlation analysis revealed that p16 exon 1 hypermethylation was associated with N/Dukes staging (p = 0.033), and p16 exon 2 hypermethylaiton was associated with T staging (p = 0.035).ConclusionsThe p16 gene body was remarkably hyper-methylated in CRC tissues and associated with p16 protein expression and cancer clinicopathological staging. The combination of p16 exon 1 and exon 2 could better reflect the overall methylation status of p16 gene body and provide potential biomarkers of CRC.

Highlights

  • Tumor suppressor gene p16 promoter hypermethylation has been widely studied in colorectal cancer (CRC), yet its clinicopathological significance remains controversial

  • A p value < 0.05 was considered statistically significant. Both exon 1 and exon 2 within p16 gene body contain a typical CpG island The p16 gene is located on Chromosome 9: 21,967, 753-21,995,301 reverse strand and its transcript variant 1 generates from 3 exons

  • In summary, the hypermethylation of exon 1 and exon 2 within p16 gene body were confirmed in CRC by a LC-MS/MS strategy

Read more

Summary

Introduction

Tumor suppressor gene p16 promoter hypermethylation has been widely studied in colorectal cancer (CRC), yet its clinicopathological significance remains controversial. The present study aimed to explore the methylation changes of p16 gene body in CRC and to find whether they were associated with clinicopathological staging of CRC. Regarding the impacts of p16 promoter hypermethylation (PHM) on CRC, some investigations revealed a correlation between it and some clinicopathological parameters or poor prognosis [10,11,12,13,14, 16], such as p16 PHM with larger tumor size, more frequent recurrence and shortened survival. Even some reported CRC patients with p16 PHM had a better survival [20] Due to those inconsistent results, the clinicopathological significance of p16 PHM remains controversial. More optimal methylation loci within p16 gene are still to be explored

Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call